Gas concentration detection device and method

Abstract

The invention provides a gas concentration detection device and method, and relates to the technical field of acoustic spectrum gas detection. The device comprises an MEMS infrared radiation light source, an eccentric photoacoustic cell, a digital MEMS microphone and data acquisition and processing equipment, the eccentric photoacoustic cell comprises a cylindrical air chamber, a first spherical reflector, a second spherical reflector and a shell, and an eccentric hole is formed in the position, deviating from the axis, of the first spherical reflector; infrared light emitted by the MEMS infrared radiation light source enters the cylindrical gas chamber, passes through a preset optical path and is absorbed by gas to be detected in the cylindrical gas chamber to generate a photoacoustic signal; converting the photoacoustic signal into a digital signal; determining the concentration of the to-be-detected gas based on the digital signal; wherein the preset optical path is determined based on the distance of the eccentric hole deviating from the axis and the curvature radius of the first spherical reflector and the curvature radius of the second spherical reflector. According to the gas concentration detection device and method provided by the invention, the detection precision of the concentration of the gas to be detected can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of photoacoustic spectroscopy gas detection, and in particular to a gas concentration detection device and method. Background Art

[0002] The non-resonant photoacoustic spectroscopy gas sensor is a commonly used optical gas sensor, which is mainly composed of an infrared radiation light source, a photoacoustic cell and an acoustic detector. It is widely used in transformer fault gas detection, gas leak detection, environmental carbon dioxide and other gas detection due to its small size and low cost. However, the infrared radiation light source it uses cannot be driven at high frequencies, and when it works in a low-frequency non-resonant mode, there are problems such as weak photoacoustic signals and susceptibility to noise interference, resulting in a low signal-to-noise ratio, making it difficult to meet the requirements of high-precision detection.

[0003] Therefore, a new technical solution is urgently needed to solve the above technical problems. Summary of the invention

[0004] The present application provides a gas concentration detection device and method to solve the defect of low gas concentration detection accuracy in the prior art.

[0005] In a first aspect, the present application provides a gas concentration detection device, comprising: a MEMS infrared radiation light source, an eccentric photoacoustic cell, a digital MEMS microphone, and a data acquisition and processing device;

[0006] The eccentric photoacoustic cell comprises a cylindrical air chamber, a first spherical reflector, a second spherical reflector and a shell; the side wall of the cylindrical air chamber is provided with an air inlet, an air outlet and a sound guide hole; the first spherical reflector and the second spherical reflector are respectively provided at two ends of the cylindrical air chamber; the first spherical reflector is provided with an eccentric hole at a position deviating from the axis; the cylindrical air chamber, the first spherical reflector and the second spherical reflector are all arranged in the shell; the MEMS infrared radiation light source is arranged opposite to the eccentric hole; the digital MEMS microphone is arranged on the outer wall of the cylindrical air chamber; the data acquisition and processing equipment is connected to the digital MEMS microphone;

[0007] The infrared light emitted by the MEMS infrared radiation light source enters the cylindrical air chamber, and after passing through a preset optical path, is absorbed by the gas to be measured in the cylindrical air chamber to generate a photoacoustic signal; the digital MEMS microphone is used to receive the photoacoustic signal and convert the photoacoustic signal into a digital signal; the data acquisition and processing equipment is used to acquire the digital signal and determine the concentration of the gas to be measured based on the digital signal; wherein the preset optical path is determined based on the distance that the eccentric hole deviates from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

[0008] Optionally, the inner wall of the cylindrical air chamber is polished and gold-plated.

[0009] Optionally, the material of the cylindrical air chamber is brass.

[0010] Optionally, the gas concentration detection device further comprises: an optical glass window and an infrared filter; the optical glass window and the infrared filter are sequentially arranged between the MEMS infrared radiation light source and the eccentric photoacoustic cell; wherein,

[0011] The optical glass window is used to transmit light and seal the eccentric photoacoustic cell;

[0012] The infrared filter is used to filter the spectrum of the infrared light, and the central wavelength and bandwidth of the infrared filter are determined based on the absorption spectrum characteristics of the gas to be measured.

[0013] Optionally, the digital MEMS microphone includes a first digital MEMS microphone and a second digital MEMS microphone, and both the first digital MEMS microphone and the second digital MEMS microphone include a sound sensitive unit; wherein,

[0014] The first digital MEMS microphone and the second digital MEMS microphone are symmetrically arranged on the outer wall of the cylindrical air chamber; the sound sensitive unit of the first digital MEMS microphone is aligned with the sound guide hole so as to be connected to the cylindrical air chamber through the sound guide hole; the sound sensitive unit of the second digital MEMS microphone is not connected to the cylindrical air chamber.

[0015] Optionally, the gas concentration detection device further comprises: a temperature sensor; the temperature sensor is arranged on the outer wall of the cylindrical gas chamber;

[0016] The temperature sensor is used to detect the current ambient temperature, and to perform temperature compensation on the current ambient temperature when the current ambient temperature is not within the preset ambient temperature range of the gas to be measured.

[0017] Optionally, the data acquisition and processing device is FPGA, DSP or MCU.

[0018] In a second aspect, the present application also provides a gas concentration detection method, which is applied to a gas concentration detection device, comprising:

[0019] Acquire the photoacoustic signal generated when the infrared light passes through a preset optical path and is absorbed by the gas to be tested;

[0020] Converting the photoacoustic signal into a digital signal;

[0021] Based on the digital signal, the concentration of the gas to be measured is determined; wherein the preset optical path is determined based on the distance of the eccentric hole of the first spherical reflector from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

[0022] In a third aspect, the present application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in the second aspect when executing the computer program.

[0023] In a fourth aspect, the present application further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the second aspect.

[0024] In a fifth aspect, the present application also provides a computer program product, including a computer program, which implements the method described in the second aspect when executed by a processor.

[0025] The gas concentration detection device and method provided in the present application can adjust the number of reflections of infrared light between the two spherical reflectors by adjusting the distance of the eccentric hole from the axis and the curvature radius of the first spherical reflector and the second spherical reflector to achieve a preset optical path, thereby ensuring that the infrared light is fully absorbed by the gas to be measured, improving the signal-to-noise ratio of the photoacoustic signal, and improving the detection accuracy of the concentration of the gas to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the present application or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 It is one of the structural schematic diagrams of the gas concentration detection device provided in the embodiment of the present application;

[0028] Figure 2 is a schematic diagram of the structure of an eccentric photoacoustic cell provided in an embodiment of the present application;

[0029] Figure 3 is a schematic diagram of the average optical path length according to the curvature radius and the eccentric distance provided in the embodiment of the present application;

[0030] Figure 4 is a simulated optical path diagram between the first spherical reflector and the second spherical reflector provided in the present application;

[0031] Figure 5It is a schematic diagram of acoustic wave signals of different concentrations of carbon dioxide provided in an embodiment of the present application;

[0032] Figure 6 Schematic diagram of the relationship between the concentration of the gas to be measured and the amplitude of the photoacoustic signal provided in the embodiment of the present application;

[0033] Figure 7 is a front cross-sectional view of a gas concentration detection device provided in an embodiment of the present application;

[0034] Figure 8 This is the second structural schematic diagram of the gas concentration detection device provided in the embodiment of the present application;

[0035] Fig. 9 It is a flow chart of a gas concentration detection method provided in an embodiment of the present application;

[0036] Fig.10 It is a schematic diagram of the structure of the electronic device provided by this application.

[0037] Reference numerals:

[0038] 1: cylindrical air chamber; 2: air inlet; 3: air outlet; 4: sound guide hole; 5: first spherical reflector; 6: second spherical reflector; 7: housing; 8: infrared filter; 9: optical glass window; 10: MEMS infrared radiation light source; 11: first circuit board; 12: support plate; 13: first digital MEMS microphone; 14: second circuit board. DETAILED DESCRIPTION

[0039] The main reasons for the low signal-to-noise ratio when using non-resonant photoacoustic spectroscopy gas sensors for gas concentration detection are: on the one hand, the thermal radiation light source has angle divergence and the light path is difficult to control, which makes it impossible to ensure that it is fully absorbed by the gas in the cavity; on the other hand, there are many noise interferences, mainly the following three types of noise: solid photoacoustic effect generated by the absorption of gas by the cavity wall of the photoacoustic pool, noise interference from the external environment, and electronic noise caused by amplifiers, filters and other circuits. Based on this, the present application provides a gas concentration detection device and method to solve the problem of low gas concentration detection accuracy.

[0040] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] Figure 1 This is one of the structural schematic diagrams of the gas concentration detection device provided in the embodiment of the present application. Figure 1 The embodiment of the present application provides a gas concentration detection device, which may include: a micro-electromechanical system (MEMS) infrared radiation light source 10, an eccentric photoacoustic cell 20, a digital MEMS microphone 30 and a data acquisition and processing device 40; the eccentric photoacoustic cell 20 includes a cylindrical air chamber 1, a first spherical reflector 5, a second spherical reflector 6 and a shell 7, the side wall of the cylindrical air chamber 1 is provided with an air inlet, an air outlet and a sound guide hole, the first spherical reflector 5 and the second spherical reflector 6 are respectively provided at both ends of the cylindrical air chamber 1, and the first spherical reflector 5 is provided with an eccentric hole at a position deviating from the axis; the cylindrical air chamber 1, the first spherical reflector 5 and the second spherical reflector 6 are all arranged in the shell 7; the MEMS infrared radiation light source 10 is arranged opposite to the eccentric hole; The digital MEMS microphone 30 is arranged on the outer wall of the cylindrical air chamber 1; the data acquisition and processing equipment 40 is connected to the digital MEMS microphone 30; the infrared light emitted by the MEMS infrared radiation light source 10 enters the cylindrical air chamber 1, and is absorbed by the gas to be measured in the cylindrical air chamber 1 after passing through a preset optical path to generate a photoacoustic signal; the digital MEMS microphone 30 is used to receive the photoacoustic signal and convert the photoacoustic signal into a digital signal; the data acquisition and processing equipment 40 is used to collect the digital signal and determine the concentration of the gas to be measured based on the digital signal; wherein the preset optical path is determined based on the distance of the eccentric hole from the axis and the curvature radius of the first spherical reflector 5 and the second spherical reflector 6.

[0042] Figure 2 It is a schematic diagram of the structure of the eccentric photoacoustic cell provided in the embodiment of the present application. Figure 2 The figure 1 is a cylindrical air chamber, the side wall holes 2 and 3 of the cylindrical air chamber are respectively the air inlet and the air outlet, and the hole 4 is the sound guide hole.

[0043] The infrared light enters the cylindrical air chamber through the eccentric hole of the first spherical reflector. The cylindrical air chamber is open at both ends. The infrared light undergoes multiple reflections on the spherical reflectors on both sides of the cylindrical air chamber, which enhances the absorption effect of the gas to be measured. The housing plays the role of assembly and isolation environment.

[0044] By using ZEMAX software to simulate the optical path, we can analyze the number of reflections and optical path of infrared light after it enters the cylindrical gas chamber. The more reflections or the longer the optical path, the more fully the infrared light is absorbed by the gas molecules to be measured, and the stronger the photoacoustic signal generated. In this application, a detector is added to the axial section in the middle of the model to count the total number of times the light passes through, and the average optical path of each light is approximately calculated by the following formula:

[0045]

[0046] Among them, l crepresents the average optical path, M represents the total number of times the light passes through, that is, the number of reflections, N represents the number of light rays, and l represents the distance between the first spherical reflector and the second spherical reflector.

[0047] Furthermore, the distance that the eccentric hole of the first spherical reflector deviates from the axis, that is, the eccentric distance is s. The change of the eccentric distance and the change of the curvature radius of the first spherical reflector and the second spherical reflector will lead to the change of the average optical path, and the average optical path of each light ray can be accumulated to obtain the preset optical path.

[0048] Figure 3 Schematic diagram of the average optical path length according to the curvature radius and the eccentric distance provided in the embodiment of the present application. Figure 3 As shown, when the distance between the first spherical reflector and the second spherical reflector is l = 30 mm, and the reflector aperture is d = 20 mm, the average optical path l c It is related to the eccentric distance s and the radius of curvature r. As the eccentric distance s increases, l c It shows a trend of increasing first and then decreasing. When s=2mm, r=26mm, l c Maximum. In this application, l is taken c The maximum value is the average optical path length l of each ray. c The preset optical path is obtained by accumulation.

[0049] The infrared light enters the cylindrical gas chamber, is continuously reflected by the first spherical reflector and the second spherical reflector, and is fully absorbed by the gas to be measured after passing through the preset optical path to generate a photoacoustic signal. After the photoacoustic signal is converted into a digital signal, the concentration of the gas to be measured can be determined. Figure 4 It is a simulated light path diagram between the first spherical reflector and the second spherical reflector provided by the present application.

[0050] The present application also detects the relationship between the photoacoustic signal and the concentration of the gas to be measured. Prepare the gas to be measured with different concentration gradients, for example: CO2 with different concentration gradients (0ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm). The modulation frequency of the light source is fixed to 10Hz, and the signal acquisition time is 1s for each concentration of CO2. Figure 5 Schematic diagram of acoustic wave signals of different concentrations of carbon dioxide provided in the embodiment of the present application. The horizontal axis Time / s represents time, and the vertical axis PA Si nga l / mPa represents the acoustic wave signal intensity of carbon dioxide. The photoacoustic fluctuation period is the same as the light source modulation frequency, and the signal swing amplitude is positively correlated with the gas concentration. Subsequently, the integral mean of the photoacoustic signal is solved and a relationship model with the concentration is established.

[0051] Figure 6Schematic diagram of the relationship between the concentration of the gas to be measured and the amplitude of the photoacoustic signal provided by the embodiment of the present application. In which, the horizontal axis Concentration / ppm represents the concentration, the vertical axis Signal / mPa represents the photoacoustic signal, Line fit represents the linear fit, and Data point represents the data point. Figure 6 As shown in the figure, there is an obvious linear relationship between the concentration of the gas to be measured and the amplitude of the photoacoustic signal. When the gas concentration increases from 0 to 3000ppm, the photoacoustic signal changes from 2.956mPa to 20.198mPa, and the sensitivity of the sensor is 6.0806uPa / ppm. Compared with the unenhanced sensor, the sensitivity of the sensor is increased by 2.517 times.

[0052] The gas concentration detection device provided in the embodiment of the present application can adjust the number of reflections of infrared light between the two spherical reflectors by adjusting the distance of the eccentric hole from the axis and the curvature radius of the first spherical reflector and the second spherical reflector to achieve a preset optical path, thereby ensuring that the infrared light is fully absorbed by the gas to be measured, improving the signal-to-noise ratio of the photoacoustic signal, and improving the detection accuracy of the concentration of the gas to be measured.

[0053] In one embodiment, the inner wall of the cylindrical air chamber is polished and gold-plated.

[0054] The gas concentration detection device provided in the embodiment of the present application reduces the interference of solid photoacoustic effect, improves the signal-to-noise ratio of the photoacoustic signal, and improves the detection accuracy of the concentration of the gas to be measured by polishing and gold-plating the cylindrical gas chamber.

[0055] In one embodiment, the material of the cylindrical air chamber is brass.

[0056] Specifically, the material of the cylindrical air chamber may be a metal with good thermal conductivity, such as brass.

[0057] The gas concentration detection device provided in the embodiment of the present application improves the signal-to-noise ratio of the photoacoustic signal by limiting the material of the cylindrical gas chamber, thereby improving the detection accuracy of the concentration of the gas to be measured.

[0058] Figure 7 is a front cross-sectional view of a gas concentration detection device provided in an embodiment of the present application. Figure 7 As shown, the gas concentration detection device also includes: an optical glass window 9 and an infrared filter 8; the optical glass window 9 and the infrared filter 8 are sequentially arranged between the MEMS infrared radiation light source and the eccentric photoacoustic cell; wherein the optical glass window 9 is used to pass light and close the eccentric photoacoustic cell; the infrared filter 8 is used to filter the spectrum of infrared light, and the central wavelength and bandwidth of the infrared filter are determined based on the absorption spectrum characteristics of the gas to be measured.

[0059] Figure 7 1 is a cylindrical air chamber, 5 and 6 are respectively the first spherical reflector and the second spherical reflector, 7 is a housing, 12 is a support plate, and the support plate 12 is screwed to the housing 7. The infrared filter 8 is used to filter the spectrum of infrared light, and its parameters such as the central wavelength and bandwidth are determined according to the absorption spectrum characteristics of the gas to be tested. For example, if the detected gas is carbon dioxide, an infrared filter with a central wavelength of 4.26um can be selected, while avoiding interference from other gases, and the bandwidth can be selected from 80-200nm. The optical glass window 9 is used to pass light and close the eccentric photoacoustic cell.

[0060] The gas concentration detection device provided in the embodiment of the present application can eliminate interference from other gases, improve the signal-to-noise ratio of the photoacoustic signal, and improve the detection accuracy of the concentration of the gas to be measured by setting an optical glass window and an infrared filter.

[0061] Figure 8 This is the second structural diagram of the gas concentration detection device provided in the embodiment of the present application. Figure 8 As shown, the digital MEMS microphone includes a first digital MEMS microphone 13 and a second digital MEMS microphone, and the first digital MEMS microphone 13 and the second digital MEMS microphone both include a sound-sensitive unit; wherein the first digital MEMS microphone 13 and the second digital MEMS microphone are symmetrically arranged on the outer wall of the cylindrical air chamber; the sound-sensitive unit of the first digital MEMS microphone 13 is aligned with the sound guide hole so as to be connected to the cylindrical air chamber through the sound guide hole; the sound-sensitive unit of the second digital MEMS microphone is not connected to the cylindrical air chamber.

[0062] Figure 8 As shown, 2 is an air inlet, 3 is an air outlet, 10 is a MEMS infrared radiation light source, 11 is a first circuit board, 13 is a first digital MEMS microphone, and 14 is a second circuit board.

[0063] The MEMS infrared radiation light source 10 is installed on the first circuit board 11 and fixed with the support plate screws. The first digital MEMS microphone 13 is soldered to the second circuit board 14. After the acoustic sensitive unit of the first digital MEMS microphone 13 is aligned with the sound guide hole, the second circuit board 14 is fixed to the side wall of the cylindrical air chamber. An identical second digital MEMS microphone is also installed on the symmetrical side of the cylindrical air chamber. The acoustic sensitive unit of the second digital MEMS microphone is not connected to the cylindrical air chamber through the sound guide hole. Therefore, the first digital MEMS microphone 13 can simultaneously detect the photoacoustic signal in the cylindrical air chamber and the external environmental noise, while the second digital MEMS microphone can only detect the external environmental noise. By calculating the different photoacoustic signals received by the first digital MEMS microphone and the second digital MEMS microphone, a photoacoustic signal with the external environmental noise removed can be obtained.

[0064] The first digital MEMS microphone 13 and the second digital MEMS microphone can also convert the detected photoacoustic signal into a digital signal output through the built-in ADC, thereby reducing the use of circuits such as amplifiers and filters.

[0065] The gas concentration detection device provided in the embodiment of the present application forms a differential acoustic detection structure by using different settings of two digital MEMS microphones, thereby being able to eliminate environmental noise and reduce electronic noise caused by circuits such as amplifiers and filters, thereby improving the signal-to-noise ratio of the photoacoustic signal and further improving the detection accuracy of the concentration of the gas to be measured.

[0066] In one embodiment, the gas concentration detection device also includes: a temperature sensor; the temperature sensor is arranged on the outer wall of the cylindrical gas chamber; the temperature sensor is used to detect the current ambient temperature, and when the current ambient temperature is not within the preset ambient temperature range of the gas to be measured, perform temperature compensation on the current ambient temperature.

[0067] like Figure 8 As shown, the temperature sensor can be soldered to the second circuit board 14 together with the first digital MEMS microphone 13, and the second circuit board 14 is fixed to the side wall of the cylindrical air chamber after the acoustic sensitive unit of the first digital MEMS microphone 13 is aligned with the sound guide hole.

[0068] The current ambient temperature will affect the absorption of infrared light spectrum by the gas to be tested. Generally speaking, the intensity of the absorption spectrum of the gas to be tested will increase with the increase of temperature, and the photoacoustic signal will be enhanced accordingly. When the temperature is low, the absorption of infrared light spectrum by the gas to be tested is weak. At this time, the current ambient temperature can be compensated to reach the preset ambient temperature range, enhance the absorption of infrared light spectrum by the gas to be tested, and enhance the photoacoustic signal.

[0069] The gas concentration detection device provided in the embodiment of the present application improves the applicable temperature range of the gas concentration detection device by using a temperature sensor to feedback the current ambient temperature and perform temperature compensation, making the gas concentration detection device more universal.

[0070] In one embodiment, the data acquisition and processing device is an FPGA, a DSP or an MCU.

[0071] like Figure 8As shown, the pins of the first circuit board 11 and the second circuit board 14 are connected to the data acquisition and processing device. The data acquisition and processing device has built-in light source driving digital circuits and sound signal processing digital circuits, such as periodic pulse wave generation circuits, cascade integrator comb filter (Cascade Integrator Comb, CIC) extraction filter circuits, orthogonal digital phase-locked amplifier circuits and universal asynchronous receiver / transmitter (UART) protocol serial port transceiver circuits.

[0072] The data acquisition and processing device may be an FPGA, a DSP or an MCU, and specifically includes a driving module for a light source, a sound wave data acquisition and processing module connected to a digital MEMS microphone, and a communication module with a computer.

[0073] The gas concentration detection device provided in the embodiment of the present application, the data acquisition and processing equipment is FPGA, DSP or MCU, and the acoustic signal acquisition and processing system implemented by FPGA, DSP or MCU has the advantages of low noise, good real-time performance and high synchronization.

[0074] Based on the above content, the working principle of the gas concentration detection device provided by the present application is as follows: the gas to be measured in the measured pipeline or in the environment enters the cylindrical air chamber through the air inlet. The data acquisition and processing equipment generates a periodic pulse signal to drive the MEMS infrared radiation light source to start emitting infrared light. The emitted infrared light passes through the optical glass window and the infrared filter in turn into the cylindrical air chamber, and is continuously reflected between the first spherical reflector and the second spherical reflector. After being fully absorbed by the gas to be measured in the cylindrical air chamber, a photoacoustic signal is generated. The generated photoacoustic signal uses gas as the transmission medium and is detected by the digital MEMS microphone through the sound guide hole. The built-in ADC chip of the digital MEMS microphone converts the photoacoustic signal into a digital signal, which is then collected by data acquisition and processing equipment such as FPGA and pre-processed by filtering, downsampling, etc., and then the concentration inversion calculation is performed to obtain the concentration of the gas to be measured.

[0075] The gas concentration detection method provided in the present application is described below. The gas concentration detection method described below and the gas concentration detection device described above can be referenced to each other.

[0076] Fig. 9 Schematic diagram of the gas concentration detection method provided in the embodiment of the present application. Fig. 9 The gas concentration detection method provided in the embodiment of the present application is applied to the above-mentioned gas concentration detection device. The method may include:

[0077] Step 910, obtaining a photoacoustic signal generated when the infrared light passes through a preset optical path and is absorbed by the gas to be measured;

[0078] Step 920: convert the photoacoustic signal into a digital signal;

[0079] Step 930: determine the concentration of the gas to be measured based on the digital signal; wherein the preset optical path is determined based on the distance that the eccentric hole of the first spherical reflector deviates from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

[0080] The gas concentration detection method provided in the embodiment of the present application can adjust the number of reflections of infrared light between the two spherical reflectors by adjusting the distance of the eccentric hole from the axis and the curvature radius of the first spherical reflector and the second spherical reflector to achieve a preset optical path, thereby ensuring that the infrared light is fully absorbed by the gas to be measured, improving the signal-to-noise ratio of the photoacoustic signal, and improving the detection accuracy of the concentration of the gas to be measured.

[0081] It should be noted here that the gas concentration detection method provided in the embodiment of the present application is based on the above-mentioned gas concentration detection device and can achieve the same technical effect. The parts and beneficial effects of this embodiment that are the same as those of the device embodiment will not be described in detail here.

[0082] Fig.10 An example of a physical structure diagram of an electronic device is shown in FIG. Fig.10 As shown, the electronic device may include: a processor 1010, a communication interface 1020, a memory 1030 and a communication bus 1040, wherein the processor 1010, the communication interface 1020 and the memory 1030 communicate with each other through the communication bus 1040. The processor 1010 may call the logic instructions in the memory 1030 to execute the gas concentration detection method, for example, including:

[0083] Acquire the photoacoustic signal generated when the infrared light passes through a preset optical path and is absorbed by the gas to be tested;

[0084] Converting the photoacoustic signal into a digital signal;

[0085] Based on the digital signal, the concentration of the gas to be measured is determined; wherein the preset optical path is determined based on the distance of the eccentric hole of the first spherical reflector from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

[0086] In addition, the logic instructions in the above-mentioned memory 1030 can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-On l yMemory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0087] On the other hand, the present application also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the gas concentration detection method provided by the above methods, for example, including:

[0088] Acquire the photoacoustic signal generated when the infrared light passes through a preset optical path and is absorbed by the gas to be tested;

[0089] Converting the photoacoustic signal into a digital signal;

[0090] Based on the digital signal, the concentration of the gas to be measured is determined; wherein the preset optical path is determined based on the distance of the eccentric hole of the first spherical reflector from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

[0091] On the other hand, the present application further provides a computer program product, the computer program product includes a computer program, the computer program can be stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, the computer can execute the steps of the gas concentration detection method provided by the above methods, for example, including:

[0092] Acquire the photoacoustic signal generated when the infrared light passes through a preset optical path and is absorbed by the gas to be tested;

[0093] Converting the photoacoustic signal into a digital signal;

[0094] Based on the digital signal, the concentration of the gas to be measured is determined; wherein the preset optical path is determined based on the distance of the eccentric hole of the first spherical reflector from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

[0095] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0096] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0097] It should also be noted that the terms "first", "second", etc. in the embodiments of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first" and "second" are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0098] In the embodiments of the present application, the term "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0099] "Determine B based on A" in the embodiments of the present application means that the factor A should be considered when determining B. It is not limited to "B can be determined based on A alone", but should also include: "Determine B based on A and C", "Determine B based on A, C and E", "Determine C based on A, and further determine B based on C", etc. In addition, it can also include taking A as a condition for determining B, for example, "When A meets the first condition, use the first method to determine B"; for another example, "When A meets the second condition, determine B", etc.; for another example, "When A meets the third condition, determine B based on the first parameter", etc. Of course, it can also be a condition that takes A as a factor for determining B, for example, "When A meets the first condition, use the first method to determine C, and further determine B based on C", etc.

[0100] In the embodiments of the present application, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A gas concentration detection device, characterized in that: include: MEMS infrared radiation light source, eccentric photoacoustic cell, digital MEMS microphone and data acquisition and processing equipment; The eccentric photoacoustic cell comprises a cylindrical air chamber, a first spherical reflector, a second spherical reflector and a shell; the side wall of the cylindrical air chamber is provided with an air inlet, an air outlet and a sound guide hole; the first spherical reflector and the second spherical reflector are respectively provided at two ends of the cylindrical air chamber; the first spherical reflector is provided with an eccentric hole at a position deviating from the axis; the cylindrical air chamber, the first spherical reflector and the second spherical reflector are all arranged in the shell; the MEMS infrared radiation light source is arranged opposite to the eccentric hole; the digital MEMS microphone is arranged on the outer wall of the cylindrical air chamber; the data acquisition and processing equipment is connected to the digital MEMS microphone; The infrared light emitted by the MEMS infrared radiation light source enters the cylindrical air chamber, and after passing through a preset optical path, is absorbed by the gas to be measured in the cylindrical air chamber to generate a photoacoustic signal; the digital MEMS microphone is used to receive the photoacoustic signal and convert the photoacoustic signal into a digital signal; the data acquisition and processing equipment is used to acquire the digital signal and determine the concentration of the gas to be measured based on the digital signal; wherein the preset optical path is determined based on the distance that the eccentric hole deviates from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

2. The gas concentration detection device according to claim 1, characterized in that: The inner wall of the cylindrical air chamber is processed by polishing and gold plating.

3. The gas concentration detection device according to claim 1, characterized in that: The material of the cylindrical air chamber is brass.

4. The gas concentration detection device according to claim 1, characterized in that: Also includes: An optical glass window and an infrared filter; the optical glass window and the infrared filter are sequentially arranged between the MEMS infrared radiation light source and the eccentric photoacoustic cell; wherein, The optical glass window is used to transmit light and seal the eccentric photoacoustic cell; The infrared filter is used to filter the spectrum of the infrared light, and the central wavelength and bandwidth of the infrared filter are determined based on the absorption spectrum characteristics of the gas to be measured.

5. The gas concentration detection device according to any one of claims 1 to 4, characterized in that: The digital MEMS microphone includes a first digital MEMS microphone and a second digital MEMS microphone, and both the first digital MEMS microphone and the second digital MEMS microphone include a sound sensitive unit; wherein, The first digital MEMS microphone and the second digital MEMS microphone are symmetrically arranged on the outer wall of the cylindrical air chamber; the sound sensitive unit of the first digital MEMS microphone is aligned with the sound guide hole so as to be connected to the cylindrical air chamber through the sound guide hole; the sound sensitive unit of the second digital MEMS microphone is not connected to the cylindrical air chamber.

6. The gas concentration detection device according to any one of claims 1 to 4, characterized in that: Also includes: A temperature sensor; the temperature sensor is arranged on the outer wall of the cylindrical air chamber; The temperature sensor is used to detect the current ambient temperature, and to perform temperature compensation on the current ambient temperature when the current ambient temperature is not within the preset ambient temperature range of the gas to be measured.

7. The gas concentration detection device according to any one of claims 1 to 4, characterized in that: The data acquisition and processing device is FPGA, DSP or MCU.

8. A gas concentration detection method, characterized in that: Applied to the gas concentration detection device according to any one of claims 1 to 7, the method comprises: Acquire the photoacoustic signal generated when the infrared light passes through a preset optical path and is absorbed by the gas to be tested; Converting the photoacoustic signal into a digital signal; Based on the digital signal, the concentration of the gas to be measured is determined; wherein the preset optical path is determined based on the distance of the eccentric hole of the first spherical reflector from the axis and the curvature radius of the first spherical reflector and the second spherical reflector.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the gas concentration detection method as claimed in claim 8 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the gas concentration detection method as claimed in claim 8 is implemented.

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